/**
 * Created by Administrator on 2019/6/9.
 */
var t = document.querySelector("#mainleft");
console.log(t);
window.onscroll = function () {

    if (document.body.scrollTop > 200 || document.documentElement.scrollTop > 200) {
        t.style.top = "120px";
        t.style.position = "fixed";
        

    }else{
        t.style.position = "static";
        
    }
    console.log(document.documentElement.scrollTop);
}
